The petroleum industry is increasingly turning to heavy oil feeds such as heavy crudes, resids, coals, tar sands, etc. as sources for feedstocks. These feedstocks are characterized by high concentrations of asphaltene rich residues, and low API gravities, with some being as low as less than 0° API.
PCT Patent Publication No. WO2008/014947, US Patent Publication No. 2008/0083650, US Patent Publication No. 2005/0241993, US Patent Publication No. 2007/0138057, and U.S. Pat. No. 6,660,157 describe processes, systems, and catalysts for processing heavy oil feeds. In embodiments of the prior art, the slurry catalyst concentration significantly increases in the last reacting zone, creating abnormal distributions of the flow within the reactor, solids deposition and unstable reactor operation. In high conversion slurry hydroprocessing units (with a conversion rate of >90%), if the solids content in the system is not properly controlled, the reactor can ultimately dry up and deposit solids reducing the effective reactor volume.
There is still a need for improved systems and methods to upgrade/treat process heavy oil feeds.